L21 - Transport Into Mitochondria And Peroxisomes

Question 1

Where is most mitochondria and peroxisomal proteins encoded?

Answer 1

Nuclear genome

Question 2

What do mitochondria’s do?

Answer 2

Primary function - energy production. Makes large amount of ATP

Question 3

How is ATP made?

Answer 3

First step - glycolysis the breakdown of glucose to pyruvate occurs in cytoplasm
Pyruvate enters mitochondria - CO2 removed from pyruvate. The remainder of the molecule enters the TCA cycle
H+ gradient

Question 4

Describe the structure of the mitochondria (3)

Answer 4

Mitochondria have a double membrane:
- Outer membrane encloses the organelle
- Inner membrane is highly folded (high SA). Folds are known as cristae
- Inner matrix contains enzymes for energy production

Question 5

What are the inner folds of mitochondria called?

Answer 5

Cristae

Question 6

Where are the enzymes responsible for energy production contained?

Answer 6

The inner matrix of mitochondria.

Question 7

What are the adaptations of the outer membrane of mitochondria?

Answer 7

They are perforated with large channels called porins which allow entry of molecules.

Question 8

What does the outer membrane contain?

Answer 8

Contains enzymes involved in mitochondrial lipid synthesis.

Question 9

What are the adaptations of the inner membrane?

Answer 9

Folded into cristae which maximises surface area

Question 10

What does the inner membrane contain and why?

Answer 10

1. Contains the REDOX performing proteins of the electron transport chain.
2. Proteins for ATP synthesis
3. Transport proteins to move molecules in and out of the matrix.

Question 11

Describe 3 things about mitochondrial genetics

Answer 11

Mitochondria contain own circular chromosome which is double stranded
Approximately 15-17kbps
Encodes for 37 genes

Question 12

What are the 3 processes of mitochondrial life cycle?

Answer 12

Fusion
Fission
Mitophagy

Question 13

What protein complexes are involved in import and assembly of proteins in the mitochondria?

Answer 13

TOM: Translocator of the Outer Membrane
SAM:Sorting and Assembly Machinery
TIM: Translocator of the Inner Membrane
OXA:Cytochrome OXidase activity

Question 14

What are the major proteins in OMM called?

Answer 14

Porins

Question 15

What are porins?

Question 16

How is the solution kept unfolded in the intermembrane space? (Check)

Answer 16

They are kept unfolded by Chaperones

Question 17

What are the two routes of getting proteins into the mitochondrial inner membrane and inter membrane space?

Answer 17

TIM23 Complex
TIM22 Complex

Question 18

What is the structure of peroxisomes?

Answer 18

1. Peroxisomes have only a single membrane.
2. They do not contain DNA or ribosomes.

Question 19

Where are peroxisomes found in the body and what they do?

Answer 19

Found in all eukaryotic cells and carry
out oxidative reactions

Question 20

Describe the peroxisomes genetics

Answer 20

Peroxisomes only have a single membrane
Do not contain DNA or ribosomes
Found in all eukaryotic cells and carry out oxidative reactions

Question 21

What types of enzymes do peroxisomes contain?

Answer 21

Contain a variety of oxidative enzymes - catalase and irate oxidase

Question 22

What is peroxisomes function ?

Answer 22

Function to remove hydrogen atoms from various organic compounds according to the reaction:

Question 23

What are most peroxisomes membrane proteins made up of?

Answer 23

Cytosol.
They are then inserted into the membrane of persisting peroxisomes.